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In this paper, a simple method of enhancing the bandwidth of the Bell-shaped UWB Antenna for indoor localization systems is proposed. Therefore, a modified version of the bell-shaped Ultra-Wide Band (UWB) antenna for indoor localization systems is presented. The proposed antenna is printed on a low-cost FR-4 substrate of 21×27×1.6mm³ size. It is composed of a bell-shaped radiating patch and a multi-slotted ground plane. The measured results show that the proposed antenna has an impedance bandwidth of about 11.2GHz ranging from 3.16GHz to 14.36GHz at S11<−10dB. Compared to the original version, an enhancement of about 5.56GHz in the measured impedance bandwidth was observed. [ABSTRACT FROM AUTHOR]

A novel multiband impulse radio ultra-wideband (MB-IR-UWB) transmitter with an energy-efficient and low-complexity pulse generator design technique compliant with the IEEE 802.15.4a standard is investigated in this paper. This transmitter is made up of a new differential narrow triangular pulse generator, a new multiband voltage-controlled oscillator (VCO), an active mixer and a variable-gain power amplifier (PA). It operates at 14 UWB bands and generates an output signal with the duration of 3 ns, more than 500 MHz of channel bandwidth and more than 20 dB of sidelobe suppression, while achieving an average energy efficiency of 51.36 pJ/pulse from 1.4-V supply. Improving spectral flexibility and worldwide compliance is the major contribution brought by this paper to make this circuit as a multifunction wireless device well suited for low-cost, low-power multiband applications. [ABSTRACT FROM AUTHOR]

This work is part of a project whose goal is the study of abnormal attenuation and distortion of the Ultra Wide Band signal "UWB" during its propagation in the human body to detect heart beats. This paper describes a method to determine the attenuation of the signal energy through the region of the body in the heart area; this region is modelled like the superposition of four semi-infinite layers, each characterized by its thickness, conductivity and dielectric constant. This method consists in seeking attenuation in biological samples of the same type as the layers forming the human body. Hence we deduce the overall attenuation in the total model. A comparison is made with other work that exists in the literature to show the robustness of our method. We adopt the FDTD method "Finite Difference Time Domain" to simulate the propagation of a Gaussian pulse whose pulse width varies from 1 to 10 GHz in these biological media. These samples should not be too thin not to have any energy fluctuation area along the sample, or too large not to risk dampening the signal especially for very short pulses. For this, we select 2.5 cm wide samples located 1 cm from the source (antenna). [ABSTRACT FROM AUTHOR]

This paper describes the method to determine the frequency of an UWB (Ultra Wide Band) wave at which the wave can cross the biological tissue with limited losses and deformation. A study on the influence of frequency variation in signal attenuation is carried especially at interfaces air-tissue and tissue-air. The biological tissue which is characterized by its thickness, its relative dielectric constant and its conductivity, is a sample of fat, localized at a distance of the antenna source which guarantees the inexistence of the attenuation at the amplitude of the electromagnetic fields in the air region. The thickness is about 2.8 cm but the conductivity and the dielectric constant vary with the frequency. The sample is localized in the middle of interest area and it is 50 cm away from transceiver antenna which send signal. A comparison is carried while applying double signals, one is a Gaussian monocycle pulse and other is a simple Gaussian pulse plane and uniform which normally tackles the surface of the samples. To calculate the attenuation of the wave in the biological tissue, we must simulate their propagation by solving Maxwell's equation in these environments. Several methods have been used such as Finite Element Method (FEM) and the Finite Differences Time Domain (FDTD) method. [ABSTRACT FROM AUTHOR]